gard to the refraction, comes out nearly 40m greater ; so tnat the refraction must have retarded sun-set by 20 minutes, and accelerated sun-rise by the same quantity.

Hecla is the most celebrated volcano of Iceland; and it would seem to argue great want of curiosity in a traveller not to visit that mountain, though at present it offers nothing very remarkable to an observer. The principal advantage which our travellers derived from their excursion to Hecla, was from it becoming the means of their seeing the Iceland Agate, or Obsidian, in its native place. A very intelligent guide, whom they there met with, told them that he could conduct them to the place where a great quantity of Iceland agates was to be found. It was situated 25 or 30 miles to the eastward of Hecla. There, in a small valley, with a lake in one corner, to which they descended with some difficulty, they saw opposite to them a perpendicular face. of rock, resembling a stream of lava. As they advanced towards it, the sun broke through the clouds; and the reflexion of his beams, from the supposed lava, quickly distinguished the Obsidian.

On ascending one of the abrupt pinnacles which arose out of this extraordinary mass of rock, we beheld a region, the desolation: of which can scarcely be paralleled. Fantastic groups of hills, craters and lava, leading the eye to distant snow-crowned jokuls; the mist rising from a water-fall; lakes embosomed among bare, bleak, mountains; an awful and profound silence; lowering clouds; marks all around of the furious action of the most destructive of the elements; -all combined to impress the mind with sensations of dread and wonder,

The fires of Hecla are not at present in a state of great activity. On its sides, the heat in one or two places under the surface was observed to be 144. When arrived at the summit, they found a crater not exceeding 100 feet in depth, with a large mass of snow in the bottom of it. The thermometer stood at 89; it was at this time about 4 in the afternoon, The thermometer, at the bottom, at 9 o'clock, had stood at 59°. They estimated the height of Hecla at about 4000 feet. The eruptions of this volcano, as far as they have been recorded, amount only to 22; none of them more ancient than 1004. Besides these, 20 other eruptions from different volcanos, have been enumerated. Of these volcanos, 6, including Hecla, may be considered as active, having erupted in the course of the last century,

No single volcanic mountain appeared to us to have thrown out much lava. This was probably owing to the vast number of apertures which have given vent to the subterraneous heat.

There

M

There is, accordingly, no country where volcanic eruptions have been so numerous as in Iceland, or have been spread over so large a surface: no part of the island is wholly free from the marks of volcanic agency.

The mineral kingdom in Iceland assumes a character highly interesting, on account of the marks of volcanic fire that are so strongly impressed almost on every object. Of this, no one who has visited this island, as far as we know, has given an account that, either for accuracy or extent of view, is at all to be compared with that which is contained in the volume before us. We have only to regret, that there is sometimes too much theory · mingled with the description, and too great a tendency to run into polemical discussion. We shall, without any theory, endeavour to give some account of the leading facts.

The rocks which compose the S. W. of Iceland, are all either of the trap formation, or they are real lava. No sandstone, or, limestone, or argillaceous strata, were any where visible. Greenstone was the most common species of trap, and in some cases basalt. These rocks are not easily distinguished from lava; and whatever opinion may be entertained of their formation, no one can deny that there is great similarity in their visible appearance. They are chiefly distinguished by this, that calcareous spar is often found in greenstone and basalt, but never in those lavas that have actually flowed on the surface. The lavas that have flowed in the open air have likewise a rugged aspect, hardly to be mistaken, acquired by their flowing and cooling at their external surface at the same time. A crust is formed as the lava flows along, that stops for a while, or retards the progress of the stream, till, by accumulation, it gathers force, and Breaks in pieces the crust, which is tossed about, and forms vast wrinkles, as it were, in the rock. The outward part of the lava is vesicular and slaggy; the interior often more compact, and in all respects similar to basalt, greenstone, &c. The lava of Hecla cannot be distinguished from some varieties of basalt; and that of Snæfel-Jokul has the same characters. Obsidian and pumice are also found in Iceland, in circumstances that leave no doubt of their volcanic origin. These resemble in all respects the stones of the same kind found in the Lipari islands, and described by Dolomieu and Spallanzani.

The volcanic origin of pumice is supported by numberless observations. Sir James Hall and Dr James Home visited a mountain on the north side of Lipari, that had escaped the survey of Dolomicu. A mass which, at a distance, they took for common lava, on a nearer approach they found to be entirely composed of obsidian and pumice, which passed into cach other.

The

The pumice had evidently flowed along with the obsidian, and formed the upper surface of the stream, which, on examination, they found to have flowed by different mouths from the great crater. The greatest breadth of this stream was about two miles and a half, and the length of it about three. Nothing can make the volcanic origin of obsidian pumice more evident than these phenomena. It is not inferred from this that they are in every case produced by fire; but it is made certain that fire does produce them in some instances.

A very remarkable fact, of which we owe the knowledge to Sir George Mackenzie, is equally favourable to the volcanic origin of pumice. About the end of January 1783, flames were observed rising out of the sea, about 30 miles off Cape Reikianes, the western point of the Guldbringe Syssel. Several small islands also appeared, which however, on subsequent examination, were not to be found; but a reef of sunk rocks now exists in the direction in which the flames were seen, terminating in what is called the Blind Rock, over which the sea breaks. The flames lasted several months; during which time, vast quantities of pumice and light slags were washed on shore all around the Gulph of Faxé. In the beginning of June, earthquakes shook the whole of Iceland; the flames in the sea disappeared, and a dreadful eruption commenced from Skaptaa Jokul, two hundred miles distant from the place where the continuance of flame over the surface of the sea, for the space of six months, had so clearly indicated the explosion of a submarine volcano.

On climbing the mountain Drapuhlid, in search of pearlstone, 'our travellers met with masses of wood mineralized in a manner 'different, we believe, from any hitherto observed. It looks like charcoal, but feels much heavier, and contains a great deal of chalcedony intersecting it in transverse fissures. It burns without flame; and when the carbonaceous matter is consumed, the substance is little altered, and its weight scarcely diminished. The Surturbrand, another kind of fossil wood peculiar to Iceland, burns with flame; and from some specimens of it, seems not at all mineralized. It is worked as timber; and Sir George 'brought with him a piece which had served for a table.

Another very singular phenomenon is here described, and is peculiar to Iceland, as far as is yet known. The mountain of Akkrefell is composed of beds from 10 to 20, nay sometimes 40 feet thick, consisting of amygdaloid, tuffa, all apparently in their original position, and in one that does not at all indicate the action of volcanic fire. Our geologists, therefore, were very much surprised when they found the under sides of many of these beds having a slaggy appearance, and bearing unequivocal marks of no slight operation of fire. This was the case at the under side of every bed, excepting those of

tuffa, as far as they ascended. They observed also a vein of greenstone, about four feet thick, cutting these beds, and having a vitreous coating on its sides, as is usual in all the veins of the country. There are similar appearances observed in some other of the Icelandic mountains; and the slag above described is sometimes united to calcareous spar. This last circumstance is certainly a proof, that the heat which produced the slag-like appearance was applied under great pressure, otherwise the calcareous spar would have been reduced to quicklime. The face of Akkre fell, where these appearances are observed, may have been the wall or side of some volcano at the bottom of the ocean: the under sides, or edges, of the beds of greenstone may have been melted, without the beds themselves having flowed.

Another of the facts brought out in this tour, will, we are persuaded, appear no less new than the preceding. Sir George was soon led to distinguish two very distinct formations of lava the one the common; the other, which he has distinguished by the name of Cavernous Lava, had no appearance of having flowed, but rather of having been melted in its place; for it appears heaved up into large bubbles, or blisters, of various forms, from a few feet to 40 or 50 in diameter. Many of them had burst, and displayed caverns of considerable depth. It was on this account the name of Cavernous Lava was given them.

This lava was traced to a great distance; it appeared to form large valleys; it was often covered by more recent lava-sometimes with sand, and very commonly with soil. The whole of the great plain below Hecla is composed of cavernous lava. It reaches from Cape Reikianes to Thingvalla, a distance of 55 nautical miles. The theory which Sir George has formed of the formation of this extraordinary rock, is, that it is one which has been softened, and even melted, by subterraneous heat, over a vast extent of surface, but without being removed from its place. This must have happened at the bottom of the sea, which is confirmed by the sand and sometimes gravel which cover it. But till volcanic countries are more carefully examined, we cannot hope for any stable theory of these singular phenomena.

Thus we have three very curious and new facts in geology brought to light by these travels. The existence of carbonized wood, containing veins of chalcedony; the slaggy beds of amygdaloid, &c. on the face of Akkrefell; and, lastly, the cavernous lava. Sir George Mackenzie, and the two gentlemen who accompanied him, entered on the examination of a volcanic country with particular advantages, in consequence of having studied the class of rocks that have the greatest affinity to lava in the great variety of these afforded by Scotland, and particularly by the country round Edinburgh; We mean the trap or whinstone rocks, so apt to be confounded with lava, and which, in a coun

try where the two are so much intermixed as in Iceland, would unavoidably be so, if the language which nature speaks had not been previously studied in one of its simplest forms.

The volume concludes with a catalogue of Icelandic minerals, of which Sir George has presented very rich collections both to the Royal Society and to the University of Edinburgh. To all this an account of the Botany and Zoology of Iceland is added by Mr Bright. A Meteorological Journal, for the year 1811, is also given; from which, if we had leisure to enlarge on it, . many curious conclusions might be deduced.

ART. IX. Religion and Policy, and the Countenance aud Assistance each should give the other. With a Survey of the Power and Jurisdiction of the Pope in the Dominions of other Princes. By Edward, Earl of Clarendon, Lord High Chancellor of England, and Chancellor of the University of Oxford. Oxford: at the Clarendon Press. 1811. 8vo. pp. 711.

FE Ew of those, we suppose, who have lately discussed the great question of religious toleration, with a reference to the Roman Catholics, expected to find a part taken in the controversy by the great Earl of Clarendon, in the year 1811. So the fact is, however; and we are glad to have an opportunity of considering the subject under some of the points of view suggested by that venerable person.

From an advertisement prefixed to this work we learn, that the manuscript from which it was printed, together with several other unpublished writings of the same author, was given by his representatives to certain trustees, for the benefit of the University of Oxford. The date of the donation is not mentioned; but we collect from the names of the parties,. that it was made in the year 1777, or in one of the six preceding years. For the publication of the work now before us, the world is indebted to the present trustees, William, Earl of Mansfield; John, Lord Bishop of London; the Right Hon. Charles Abbot, Speaker of the House of Commons; and the Rev. Dr Cyril Jackson, late Dean of Christ-Church, Oxford.

The title of the book, which appears to proceed from the author himself, is very ill calculated to apprize the reader of the nature of its contents. Of the 711 pages which it contains, 636 are occupied in an historical development of the rise, progress and decline of the Papal authority; beginning with the foundation of the Church of Rome, and ending with the reign of Clement X, who was elected in the year 1670. The remaining 75 pages are divided between a short introduction of 11 pages, and a chapter entitled, Concluding Observatious upon the Pope's U